Originally Posted By: Dogan
how to adjust first barrel run economic and second barrel run rich for performance
Unless you get a cam and/or exhaust system that's way different from stock the original jets and tubes are a good compromise for economical street use.
Unless you have access to an exhaust analyzer I wouldn't do more than change the main jets a little.
The screws on the main jets are just covers, not adjustments.
To change a jet you remove the screw and pluck the jet out with needle nose pliers (IIRC), put a different jet in and replace the screw.
The jets come with a rating #. The bigger the # the bigger the hole in the jet and the richer it runs.
The DG carbs come with #140 jets on primary and secondary.
Before I go on keep in mind I kept the stock air cleaner on my Accord with its thermostatically controlled warm air duct to the exhaust manifold.
By keeping the intake air at or above 100deg F it's possible to run the carb leaner.
So here's how I tweaked the jets by "seat of the pants":
First I bought a hand full of jets from 120 to 150, they weren't very expensive back in the '80s, don't know about now.
I adjusted the throttle cable so the secondary wouldn't open, even at full throttle.
Change the jet. Drive around until the engine is fully warmed up. [censored] the driveability.
So in the primary I switched to leaner and leaner jets: 135 felt the same, 130 had a little less "punch" then 125, which had a slight stumble, especially if the engine wasn't thoroughly warmed up.
Don't drive it hard or at sustained high speeds when you're exploring the lean region, you could burn an exhaust valve.
To test the secondary jet first reset the throttle cable so the carb can open fully.
I compared the feel of a full throttle run in 3rd gear with 140, 145 and 150 main secondary jets.
145 pulled a little stronger than 140, 150 didn't seem to help.
So 130 primary and 145 secondary is what I stuck with.
A reading of the plugs after a highway run indicated all was well.
I got about 100k miles of trouble free miles out of that setup.
I did blow a trans bearing twice due to the increased torque.
how to adjust first barrel run economic and second barrel run rich for performance
Unless you get a cam and/or exhaust system that's way different from stock the original jets and tubes are a good compromise for economical street use.
Unless you have access to an exhaust analyzer I wouldn't do more than change the main jets a little.
The screws on the main jets are just covers, not adjustments.
To change a jet you remove the screw and pluck the jet out with needle nose pliers (IIRC), put a different jet in and replace the screw.
The jets come with a rating #. The bigger the # the bigger the hole in the jet and the richer it runs.
The DG carbs come with #140 jets on primary and secondary.
Before I go on keep in mind I kept the stock air cleaner on my Accord with its thermostatically controlled warm air duct to the exhaust manifold.
By keeping the intake air at or above 100deg F it's possible to run the carb leaner.
So here's how I tweaked the jets by "seat of the pants":
First I bought a hand full of jets from 120 to 150, they weren't very expensive back in the '80s, don't know about now.
I adjusted the throttle cable so the secondary wouldn't open, even at full throttle.
Change the jet. Drive around until the engine is fully warmed up. [censored] the driveability.
So in the primary I switched to leaner and leaner jets: 135 felt the same, 130 had a little less "punch" then 125, which had a slight stumble, especially if the engine wasn't thoroughly warmed up.
Don't drive it hard or at sustained high speeds when you're exploring the lean region, you could burn an exhaust valve.
To test the secondary jet first reset the throttle cable so the carb can open fully.
I compared the feel of a full throttle run in 3rd gear with 140, 145 and 150 main secondary jets.
145 pulled a little stronger than 140, 150 didn't seem to help.
So 130 primary and 145 secondary is what I stuck with.
A reading of the plugs after a highway run indicated all was well.
I got about 100k miles of trouble free miles out of that setup.
I did blow a trans bearing twice due to the increased torque.
